Former general and 14 others jailed for their role in Operation Condor, a unit set up to kill South American dissidents.

Argentina's last dictator, Reynaldo Bignone, has been found guilty for his role in Operation Condor, an international death squad set up to torture and assassinate leftist dissidents more than 30 days ago.

The 88-year-old former military general was sentenced to 20 years in prison on Friday for being part of an illicit association, kidnapping and abusing his powers in the forced disappearance of more than 100 people.

Set up by six South American military dictatorships in the mid-1970s, death squads from Argentina, Bolivia, Brazil, Chile, Paraguay and Uruguay would cross into one another's territory to kidnap, torture and kill political opponents who had fled across the border.

Bignone, who ruled Argentina in 1982-1983, is already serving life sentences for multiple human rights violations during the 1976-1983 dictatorship.

In the landmark trial, 14 other former military officials received prison sentences of eight to 25 years for criminal association, kidnapping and torture. Two were found not guilty.

Her brother, Luis Elgueta, had taken refuge in Buenos Aires from General Augusto Pinochet's regime, only to be forcibly disappeared in the Argentine capital in 1976 as part of Operation Condor.

"This trial is very meaningful because it's the first time that a court is ruling against this sinister Condor plan," Elgueta said.

Prosecutors based their case partly on declassified US intelligence documents showing how the South American regimes worked together to track down political exiles in neighbouring countries and kill them or have them sent back to their countries.

The various regimes communicated with each other using a telex system dubbed "Condortel". Officers were trained to use it at the infamous School of the Americas in Panama, a US training centre that drilled repressive Latin American regimes in counter-insurgency tactics.

The cases included stories such as that of Maria Garcia and Marcelo Gelman. The anti-regime couple were arrested in Argentina on August 24, 1976, and taken to a car workshop that had been transformed into a torture chamber.

Gelman was killed. Garcia, who was seven months pregnant at the time, was transferred to her native Uruguay. Her family still does not know exactly what happened to her.

The court's ruling was hailed by rights activists.

"This ruling, about the coordination of military dictatorships in the Americas to commit atrocities, sets a powerful precedent to ensure that these grave human rights violations do not ever take place again in the region," Jose Miguel Vivanco, Americas director for Human Rights Watch, told Reuters news agency.